Table Of ContentFluid Mechanics and Its Applications
S. Harikrishnan
A. D. Dhass
Hafiz Muhammad Ali
Thermal
Performance
of Nanofluids in
Miniature Heat
Sinks with Conduits
Fluid Mechanics and Its Applications
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Volume 131
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· ·
S. Harikrishnan A. D. Dhass
Hafiz Muhammad Ali
Thermal Performance
of Nanofluids in Miniature
Heat Sinks with Conduits
S.Harikrishnan A.D.Dhass
DepartmentofMechanicalEngineering DepartmentofMechanicalEngineering
KingsEngineeringCollege IndusInstituteofTechnology
Chennai,TamilNadu,India andEngineering(IITE)
IndusUniversity
HafizMuhammadAli Ahmedabad,Gujarat,India
DepartmentofMechanicalEngineering
andInterdisciplinaryResearchCenterfor
RenewableEnergyandPowerSystems
(IRC-REPS)
KingFahdUniversityofPetroleum
andMinerals
Dhahran,SaudiArabia
ISSN0926-5112 ISSN2215-0056 (electronic)
FluidMechanicsandItsApplications
ISBN978-981-16-7844-8 ISBN978-981-16-7845-5 (eBook)
https://doi.org/10.1007/978-981-16-7845-5
©TheEditor(s)(ifapplicable)andTheAuthor(s),underexclusivelicensetoSpringerNature
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Preface
Heat dissipation requirements have drawn much interests in the last two decades
as a result of rapid advancements in a wide range of technologies, particularly in
miniaturedevices.High-performanceheatsinksareindemandtoensurethequality
andlonglifeofthesedevices.Thedemandforanextremelyhighflowvelocity,aswell
astherelatednoiseandvibrationdifficulties,haslimitedtheuseofforcedconvection
cooling. Owing to the potential of heat carrying capability, the microchannel heat
sinkappearstobethemostreliablecoolingmethod.
ItgivesusimmensepleasuretointroducethebooktitledThermalPerformance
ofNanofluidsinMiniatureHeatSinkswithConduits,anditcomprisesfivechapters,
coveringfromfundamentalsofminiatureheatsinkusingnanofluidstoapplications.
The book starts with types of nanofluids, preparation techniques, thermophysical
properties of the nanofluids and types of heat sinks. Flow characteristics of the
nanofluids in the miniature heat sinks are discussed with respect to different flow
patterns.Next,themodificationofdesignmadeinminiatureheatsinkandfabrication
process of various conduit miniature heat sinks are included. Then, heat transfer
characteristics of the various conduits carrying nanofluids are elaborated. Lastly,
variousapplicationsoftheminiatureheatsinksarediscussedindetail.
Thisbookcouldbebeneficialtothegraduates,researchscholarsandresearchers
asitcouldcatertheirneeds.Suggestionsandcommentsfromthereadersarehighly
appreciatedtoimprovethequalityofthecontentscomprisedinthebook.
Chennai,India S.Harikrishnan
Ahmedabad,India A.D.Dhass
Dhahran,SaudiArabia HafizMuhammadAli
Acknowledgement HafizMuhammadAliacknowledgesthesupportofKingFahd
UniversityofPetroleumandMinerals,Dhahran31261,SaudiArabia.
v
Contents
1 Nanofluids ...................................................... 1
1.1 Introduction ............................................... 1
1.1.1 Nanofluid .......................................... 1
1.2 MiniatureHeatSink ........................................ 3
1.3 TypesofNanofluids ........................................ 5
1.3.1 BaseFluid ......................................... 5
1.3.2 MetallicNanoparticles ............................... 5
1.3.3 OxideNanoparticles ................................. 7
1.3.4 CarbonNanoparticles ............................... 8
1.3.5 Nanodroplet ........................................ 9
1.3.6 Surfactant ......................................... 10
1.4 TypesofHeatSink ......................................... 11
1.5 BasedonManufacturingMethods ............................ 11
1.5.1 ActiveHeatSink .................................... 11
1.6 BasedonShape ............................................ 12
1.7 PreparationofNanofluids .................................... 14
1.7.1 SingleStepMethod ................................. 14
1.7.2 Two-StepMethod ................................... 18
1.8 CharacterizationofNanofluids ............................... 18
1.8.1 CompositionoftheNanofluid ........................ 19
1.8.2 LoadingofNanoparticles ............................ 20
1.8.3 ImpuritiesinNanofluid .............................. 20
1.8.4 StabilityofNanofluid ............................... 21
1.8.5 ThermalConductivityofNanofluid .................... 22
1.8.6 ViscosityofNanofluid ............................... 23
1.8.7 SpecificHeatofNanofluid ........................... 23
1.8.8 SpecificGravityofNanofluid ......................... 25
1.8.9 ElectricalConductivityofNanofluid ................... 25
vii
viii Contents
1.8.10 MagneticPropertyofNanofluid ....................... 25
1.8.11 OpticalPropertyofNanofluid ........................ 26
References ...................................................... 26
2 FlowCharacteristicsofNanofluidsinHeatSinks ................... 29
2.1 Introduction ............................................... 30
2.2 FlowCharacteristics ........................................ 33
References ...................................................... 42
3 FlatFinHeatSinkwithForcedConvection ........................ 45
3.1 Introduction ............................................... 46
3.2 FlatFinHeatSinkwithForcedConvection ..................... 46
3.3 OptimizedHeatSinkTopology ............................... 49
3.4 GoverningEquations ....................................... 51
3.5 DesignVariables ........................................... 52
3.6 StraightChannel ........................................... 53
3.7 WavyChannel ............................................. 54
3.8 Pin–Fin ................................................... 54
3.9 Ribs ...................................................... 55
3.10 ObliqueFinChannel ........................................ 56
References ...................................................... 57
4 HeatTransferEnhancementintheMicroChannelHeatSinks ....... 59
4.1 Introduction ............................................... 60
4.2 MicrochannelHeatsink ...................................... 61
4.3 StructuralBasedBifurcation ................................. 62
4.4 DoubleLayerMicrochannel ................................. 63
4.5 EffectofMicrochannelShapes ............................... 66
4.6 HeatTransferEnhancingTechniques .......................... 67
4.7 GeometricModifications .................................... 67
4.8 Nanofluids ................................................ 73
References ...................................................... 79
5 ApplicationsofMiniatureHeatSink .............................. 83
5.1 Potential Engineering Applications of Nanofluids
intheMiniatureChannels ................................... 84
5.1.1 HeatExchanger .................................... 84
5.1.2 ElectronicCooling .................................. 85
5.1.3 SolarCooling ...................................... 86
5.1.4 RefrigerationandOtherSpecializedCooling ............ 86
5.2 BiomedicalSystems ........................................ 87
5.3 SpaceandDefense ......................................... 87
5.4 OtherApplications ......................................... 88
5.5 Application ................................................ 92
References ...................................................... 95
Chapter 1
Nanofluids
Abstract Nanofluidsarecolloidalsuspensionsofnanoparticleswithsizesranging
from one to one hundred nanometers in size. Nanofluids have been the subject of
momentous study for the last fifteen years, owing to their increased thermal prop-
erties.Inengineeringequipment,thelowthermalconductivityofconventionalheat
transferfluidhasshowntobeasignificanthindrancetoenhancingtheperformance
andcompactnessoftheequipment.Theuseoftinyparticlesinnanoscaledispersed
inconventionalheattransferfluidscanovercomethesechallenges.Herein,different
synthesistechniquesofnanoparticlesarediscussedindetail.Therearetwomethods
employedforthepreparationofnanofluidsandtheirsignificanceisincluded.Ultra-
sonicationisacriticalstepinthepreparationprocessbecauseofitsroleinstabilizing
and enhancing thermophysical characteristics. Further, the effect of nanoparticles
on the viscosity of the nanofluids is included as the enhancement of the viscosity
deceleratestheheattransfer.
Contents
Thischaptercomprisestheintroductionofnanofluidsandminiatureheatsink,
typesofnanofluidsandheatsinks,preparationofnanofluids,characterization
ofnanofluidsandthermophysicalpropertiesofnanofluids.
1.1 Introduction
1.1.1 Nanofluid
Fluids are widely used as hot carriers in heat transportation systems.As far as the
applicationsofheattransferfluidsareconcerned,hydrothermalheatingandcooling
©TheAuthor(s),underexclusivelicensetoSpringerNatureSingaporePteLtd.2022 1
S.Harikrishnanetal.,ThermalPerformanceofNanofluidsinMiniatureHeatSinks
withConduits,FluidMechanicsandItsApplications131,
https://doi.org/10.1007/978-981-16-7845-5_1
2 1 Nanofluids
systems, transport cooling systems, petrochemical heating and cooling systems,
textiles,etc.arewidelyused.Themixtureofconventionalbaseliquidandmeasured
nanometerpartitionsisknownasNanofluid.Usingnanofluids,lowthermalconduc-
tivity of base fluids such as air, ethylene glycol and propylene glycol, oil can be
replaced. Nanofluids can be used for manufacturing, metal working related uses,
heating,ventilation,storage,attractivemedicineandafewmore,duetotheircapti-
vating physical characteristics [1]. Many researchers have suggested that one of
the main requirements for enhancing the heat transfer is the effect of Brownian
motion.Brown’smovementisinducedbysmalldistortionsofthefluidformulation
oftemperatureandvelocity.
Heatexchangersareemployedtofacilitatetheheatexchangingprocessbetween
two fluids at different temperatures. Nanofluids used in the heat exchangers are
utilized as coolants in automotive and nuclear reactor heat transfer medium. If
nanoparticles are suspended in the base fluids ensuring uniform dispersion, then
itcanbecalledasNanofluids.Thesizesofthenanoparticles aretypicallyranging
from1to100nmhowever,theirlengthsandshapescanbeslightlydifferent[2,3].
Nanoparticlesare1000timeshigherinsurfaceareaforagivenmassorvolume
than normal particles and thus, they have higher suspension stability, improved
thermal transport capability with less particle agglomeration and flexible proper-
ties.Furthermore,highthermalconductivity,smallpressuredropsandmechanical
degradation make nanofluids highly functional for various industrial applications
includingmicroelectronics,transport,space,biomedical,nuclear,solarandcooling
systems[4].
A high rate of heat transfer is being pursued for increased requirements for
personal computer CPUs and laptop for processing and storage requirements. The
supplyofdifferentgeometriesofnanofluidstoaheatpipeisasaferchoice.Theuse
ofnanofluidsisaviablechoicetoincreasetheengine’scoolingrateandreducethe
complexityoftheengine.Inparticular,improvedheattransferratesarecontributing
to the production of lightweight and compact radiators for heavy-duty engines in
particular.Morespecificviscositycorrelationsaregivenbythenanofluidflowanal-
ysisduetotheeffectofparticlelength,aggregation,sonicationtimeandpH,along
withparticleconcentration[5].
Usually, nanofluids have greater heat transport properties than conventional
liquids,witnessedthroughdifferentexperimentalandtheoreticaltests.Forexample,
adding0.3%volumeofcoppernanoparticleswithethyleneglycol,itincreasedthe
thermalconductivityby40%.Dispersionofnanoparticlesinthebasefluidimproves
notjustthethermalconductivitybutalsotheconvectiveheattransfervalues,which
alsoenhancesthetemperaturediffusionduetohigherheattransferrange.Theengine
coolingsystemusingnanofluidisthelatestfoundationfortechnologicalintegration
and growth. Nanofluids are ideal coolants owing to their high thermal diffusive-
ness and a fast response to thermal changes. In contrast with pure fluid, the pres-
ence of nanoparticles in nanofluids helps to improve the mixing flow and thermal
conductivity[6].
